DE 202 21 562 U1 discloses a wind turbine with a tower oscillation monitoring. The wind turbine is equipped with a control device for the control system of the wind turbine, and with a device for detection of the oscillation movement of the tower. The wind turbine is equipped with means for detecting an oscillation of the tower. If it is found that the tower oscillation and/or the absolute deflection of the tower exceed/exceeds a predeterminable first threshold value, the control system is changed to prevent a further excitation of the tower oscillation. It is also known for the first natural frequency of the tower to be measured with the aid of the means for detection of the tower oscillation.
U.S. Pat. No. 8,044,670 discloses a method for determining the first tower natural frequency. For this purpose, measured acceleration values are evaluated with the aid of a Fourier transformation, and the tower natural frequencies are determined using a spectral vector.
EP 2 063 110 A1 discloses a method for damping oscillations at the tower of a wind turbine. For this purpose, the rotor rotational speed is modified by changing the blade pitch angle depending on a tower oscillation.
U.S. patent application publication 2010/0289266 discloses a method for operating a wind turbine, in which the blade pitch angle for each rotor blade is changed as a function of a lateral oscillation of the tower in order to damp the lateral oscillation of the tower induced by the external wind movement.
U.S. Pat. No. 4,266,911 discloses a method for the installation of a wind turbine in which a tower is supported during installation by guyed cables such that its first natural oscillation frequency is not excited while the nacelle is being fitted.
DE 197 39 164 B4 discloses a wind turbine having a rotor in which a yaw and/or pitch actual moment exerted on the rotor is detected, and is reduced by adjusting the blade pitch angle.
U.S. Pat. No. 7,708,524 discloses a method for identification of a lateral tower acceleration, which is used for identification of asymmetric ice accumulation on the rotor blades. For this purpose, the lateral acceleration of the tower is compared with the frequency of the rotor blades.
U.S. Pat. No. 7,423,352 discloses a method for damping oscillations of a wind turbine in which the generator torque is regulated as a function of the generator rotational speed and a resonant frequency.
U.S. Pat. No. 7,400,055 discloses a wind turbine in which a lateral tower oscillation is measured and is damped by regulating the torque of the generator and the blade pitch angle.
U.S. Pat. No. 6,891,280 discloses a method for operating an offshore wind turbine in which a rotational speed which can lead to excitation of the critical tower natural frequency is prevented by an open-loop control of the wind turbine.